Re: BUILDING A SURFACE COLUMN

["David L Parkhurst" <dlpark@xxxxxxxx>]

I think PHREEQC will do what you want. Here is an example where pure water
is reacted with calcite (.01 mole) and CO2 to generate the initial
conditions for a column, but only the first cell of the column has CO2 at
the beginning of the ADVECTION step. Whenever you SAVE a solution or
equilibrium_phases, it replaces any previous definitions for the numbers to
which it is saved. ADVECTION automatically saves solutions,
equilibirium_phases, exchangers, etc after each advective step.

David

SOLUTION 1
END
EQUILIBRIUM_PHASES 1
      Calcite     0.0   0.010
      CO2(g)      -2    10.
END
USE solution 1
USE equilibrium_phases 1
SAVE solution 1-10
SAVE equilibrium_phases 1
END
EQUILIBRIUM_PHASES 2-10
      Calcite 0.0 0.01
END
SOLUTION 0
END
ADVECTION
      -shifts 10
      -cells      10
END





David Parkhurst (dlpark@xxxxxxxx)
U.S. Geological Survey
Box 25046, MS 413
Denver Federal Center
Denver, CO 80225


                                                                                                                     
                      "George Moncure"                                                                               
                      <hydro-geo@xxxxx         To:      "David L Parkhurst" <dlpark@xxxxxxxx>                        
                      .com>                    cc:                                                                   
In-Reply-To: <001101c13875$d708ece0$1f8be30c@xxxxxxxxx>
                                               Subject: BUILDING A SURFACE COLUMN                                    
                      09/08/01 08:52                                                                                 
                      AM                                                                                             
                                                                                                                     
                                                                                                                     



Dr. Parkhurst,

In the ADVECTI0N example 11, an equilibrium a defined solution was used for
a defined exchange column.  Instead, I wish to generate the column (Sufrace
in this case) as well as the equilib solution in it during the first
Simulation(s), rather than specifying them.  THen I wish to let a different
water "pass through it".

I have done such discretely on a single 1 L volume (or cell) to my
satisfaction.  But because a column concept is more appropriate, as many as
100 or 200 cells may be needed.  I decided that ADVECTION would be
appropriate but do not know how to:

(1)  specify a Solution (say Solution 1) that reacts inside a cell(s) and
generates solids and an equilibrium solution then specify re-identify that
SOLUTION 1, REACTION 1, EQUILIBRIUM PHASES 1, SURFACE 1 are reassigning
Solution, Phases, and Surface to the 50 column cells, such as Solution 1-50
- they already "own" the name "1"

(2)  or better yet, generate the column using the same Solution, Reaction,
Phases, and Surface by chaining in one step such as:

SOLUTION 0                                groundwater
SOLUTION 1-4                              groundwater
(defined)
REACTION 1-4                              FeSO4 dissolving into solution
(reaction defined)
EQUILIBRIUM PHASES 1-4          Fe(OH)3 and others
(list of phases etc)
SURFACE 1-4                              Hfo
(surfaces and characteristics)

but this does not work as planned.

(3)  Since the column is an aquifer and chemicals to make the Surfaces are
to be injected by well, there is a dynamic element that would be nice to
consider in another model - reactions will occur closest to the well first,
chromatographically.

Obviously I am not clear how to shape my model concepts in terms of
PHREEQC's functions.

Do you have an example or suggestions?

Thanks for you help,

George Moncure